— How about buying an iPhone 4s for your mother’s birthday?— Oh maybe it’s too expensive

问题补充：

— How about buying an iPhone 4s for your mother’s birthday?

— Oh, maybe it’s too expensive, Dad. Do you know ?

A. how much does it cost

B. how much it costs

C. how much it cost

D. how much did it cost

答案：

A. how much does it cost

(答案→)B. how much it costs

C. how much it cost

D. how much did it cost

解析：本题是特殊疑问句作宾语从句，要用陈述句语序。故选B